// Marzban API Client для Next.js
// Безопасная интеграция без изменений на production сервере

export interface MarzbanUser {
  username: string;
  status: 'active' | 'limited' | 'expired' | 'disabled';
  used_traffic: number; // bytes
  data_limit: number | null; // bytes, null = unlimited
  expire: number | null; // Unix timestamp, null = unlimited
  sub_updated_at: string; // ISO 8601 datetime
  on_hold_expire_duration: number;
  on_hold_timeout: string | null;
}

export interface MarzbanUsage {
  date: string; // YYYY-MM-DD
  upload: number; // bytes
  download: number; // bytes
  total: number; // bytes
}

export interface MarzbanUsageResponse {
  username: string;
  usages: MarzbanUsage[];
}

export interface SubscriptionUserInfo {
  upload: number;
  download: number;
  total: number;
  expire: number;
}

export class MarzbanApiClient {
  private baseUrl: string;
  private cache: Map<string, { data: any; timestamp: number }>;
  private readonly CACHE_TTL = 60000; // 1 минута

  constructor(baseUrl: string = 'https://umbrix2.3to3.sbs') {
    this.baseUrl = baseUrl;
    this.cache = new Map();
  }

  /**
   * Get user subscription info from Marzban API
   * Falls back to HTML scraping if API fails
   * 
   * @param token - Subscription token (base64 encoded)
   * @returns User subscription details
   */
  async getUserInfo(token: string): Promise<MarzbanUser> {
    // Проверяем кеш
    const cached = this.cache.get(`info_${token}`);
    if (cached && Date.now() - cached.timestamp < this.CACHE_TTL) {
      return cached.data;
    }

    try {
      // ✅ Try API first
      const response = await fetch(`${this.baseUrl}/sub/${token}/info`, {
        headers: {
          'Accept': 'application/json',
        },
      });

      if (response.ok) {
        const data = await response.json();
        this.cache.set(`info_${token}`, { data, timestamp: Date.now() });
        return data;
      }

      if (typeof window === 'undefined') console.warn('API endpoint returned error:', response.status, response.statusText);
    } catch (apiError) {
      if (typeof window === 'undefined') console.warn('API failed, falling back to HTML scraping:', apiError);
    }

    // ❌ Fallback to HTML scraping (старый метод)
    try {
      const response = await fetch(`${this.baseUrl}/sub/${token}/`, {
        headers: {
          'Accept': 'text/html',
        },
      });

      if (!response.ok) {
        throw new Error(`HTTP error ${response.status}`);
      }

      const html = await response.text();
      const data = this.parseHtmlResponse(html);
      this.cache.set(`info_${token}`, { data, timestamp: Date.now() });
      return data;
    } catch (fallbackError) {
      if (typeof window === 'undefined') console.error('Both API and HTML scraping failed:', fallbackError);
      throw new Error('Не удалось загрузить данные подписки');
    }
  }

  /**
   * Parse HTML response (fallback method)
   * @private
   */
  private parseHtmlResponse(html: string): MarzbanUser {
    // Username
    const usernameMatch = html.match(/<h2[^>]*>([^<]+)<\/h2>/);
    const username = usernameMatch ? usernameMatch[1].trim() : 'Unknown';

    // Status
    const statusMatch = html.match(/badge--(\w+)/);
    let status: 'active' | 'limited' | 'expired' | 'disabled' = 'active';
    if (statusMatch) {
      const statusClass = statusMatch[1];
      if (statusClass === 'success' || statusClass === 'active') status = 'active';
      else if (statusClass === 'warning' || statusClass === 'limited') status = 'limited';
      else if (statusClass === 'error' || statusClass === 'expired') status = 'expired';
      else status = 'disabled';
    }

    // Traffic
    const trafficMatch = html.match(/(\d+(?:\.\d+)?)\s*GB\s*(?:\/|из)\s*(\d+)\s*GB/);
    const usedTrafficGB = trafficMatch ? parseFloat(trafficMatch[1]) : 0;
    const totalTrafficGB = trafficMatch ? parseFloat(trafficMatch[2]) : 0;

    const used_traffic = usedTrafficGB * 1024 * 1024 * 1024;
    const data_limit = totalTrafficGB > 0 ? totalTrafficGB * 1024 * 1024 * 1024 : null;

    // Expire date
    const expireMatch = html.match(/Действительна до[:\s]*([^<]+)/);
    let expire: number | null = null;
    if (expireMatch && expireMatch[1].trim() !== '∞') {
      const dateStr = expireMatch[1].trim();
      const dateParts = dateStr.match(/(\d{2})\.(\d{2})\.(\d{2,4})/);
      if (dateParts) {
        const day = parseInt(dateParts[1]);
        const month = parseInt(dateParts[2]) - 1;
        const year = parseInt(dateParts[3]);
        const fullYear = year < 100 ? 2000 + year : year;
        expire = Math.floor(new Date(fullYear, month, day).getTime() / 1000);
      }
    }

    return {
      username,
      status,
      used_traffic,
      data_limit,
      expire,
      sub_updated_at: new Date().toISOString(),
      on_hold_expire_duration: 0,
      on_hold_timeout: null,
    };
  }

  /**
   * Get user traffic usage history
   * 
   * @param token - Subscription token
   * @param start - Start date (YYYY-MM-DD) optional
   * @param end - End date (YYYY-MM-DD) optional
   * @returns Usage statistics
   */
  async getUserUsage(
    token: string,
    start?: string,
    end?: string
  ): Promise<MarzbanUsageResponse> {
    const cacheKey = `usage_${token}_${start || ''}_${end || ''}`;
    const cached = this.cache.get(cacheKey);
    if (cached && Date.now() - cached.timestamp < this.CACHE_TTL) {
      return cached.data;
    }

    const params = new URLSearchParams();
    if (start) params.append('start', start);
    if (end) params.append('end', end);

    const url = `${this.baseUrl}/sub/${token}/usage${
      params.toString() ? '?' + params.toString() : ''
    }`;

    const response = await fetch(url, {
      headers: {
        'Accept': 'application/json',
      },
    });

    if (!response.ok) {
      throw new Error(`Marzban API error: ${response.status} ${response.statusText}`);
    }

    const data = await response.json();
    this.cache.set(cacheKey, { data, timestamp: Date.now() });
    return data;
  }

  /**
   * Get subscription config for specific client type
   * 
   * @param token - Subscription token
   * @param clientType - Client type (sing-box, clash-meta, v2ray, etc.)
   * @returns Config file (YAML/JSON/base64)
   */
  async getSubscriptionConfig(
    token: string,
    clientType: 'sing-box' | 'clash-meta' | 'clash' | 'outline' | 'v2ray' | 'v2ray-json'
  ): Promise<string> {
    const response = await fetch(`${this.baseUrl}/sub/${token}/${clientType}`, {
      headers: {
        'Accept': clientType.includes('clash') ? 'text/yaml' : 'application/json',
      },
    });

    if (!response.ok) {
      throw new Error(`Marzban API error: ${response.status} ${response.statusText}`);
    }

    return response.text();
  }

  /**
   * Parse subscription-userinfo header from response
   * 
   * @param headers - Response headers from /sub/{token}/ endpoint
   * @returns Parsed user info
   */
  parseSubscriptionUserInfo(headers: Headers): SubscriptionUserInfo {
    const userInfo = headers.get('subscription-userinfo');
    if (!userInfo) {
      throw new Error('subscription-userinfo header not found');
    }

    const parsed: any = {};
    userInfo.split(';').forEach((pair) => {
      const [key, value] = pair.trim().split('=');
      parsed[key] = parseInt(value, 10);
    });

    return {
      upload: parsed.upload || 0,
      download: parsed.download || 0,
      total: parsed.total || 0,
      expire: parsed.expire || 0,
    };
  }

  /**
   * Format bytes to human-readable string
   */
  formatBytes(bytes: number, decimals: number = 2): string {
    if (bytes === 0) return '0 Bytes';

    const k = 1024;
    const dm = decimals < 0 ? 0 : decimals;
    const sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB'];

    const i = Math.floor(Math.log(bytes) / Math.log(k));

    return parseFloat((bytes / Math.pow(k, i)).toFixed(dm)) + ' ' + sizes[i];
  }

  /**
   * Format Unix timestamp to Russian date string
   */
  formatExpireDate(timestamp: number | null): string {
    if (timestamp === null || timestamp === 0) {
      return '∞ Безлимитная';
    }

    const date = new Date(timestamp * 1000);
    return date.toLocaleDateString('ru-RU', {
      day: '2-digit',
      month: '2-digit',
      year: 'numeric',
    });
  }

  /**
   * Calculate days until expiration
   */
  getDaysUntilExpire(timestamp: number | null): number | null {
    if (timestamp === null || timestamp === 0) {
      return null; // Unlimited
    }

    const now = Date.now() / 1000;
    const diff = timestamp - now;
    return Math.ceil(diff / (24 * 60 * 60));
  }

  /**
   * Get status color class based on status and days remaining
   */
  getStatusColor(status: string, daysRemaining: number | null): string {
    if (status === 'expired') {
      return 'text-red-500 bg-red-500/10 border-red-500/20';
    }
    if (status === 'limited') {
      return 'text-yellow-500 bg-yellow-500/10 border-yellow-500/20';
    }
    if (status === 'disabled') {
      return 'text-slate-400 bg-slate-500/10 border-slate-500/20';
    }
    if (daysRemaining !== null && daysRemaining <= 7) {
      return 'text-yellow-500 bg-yellow-500/10 border-yellow-500/20';
    }
    return 'text-green-500 bg-green-500/10 border-green-500/20';
  }

  /**
   * Get status text in Russian
   */
  getStatusText(status: string): string {
    switch (status) {
      case 'active':
        return 'Активна';
      case 'limited':
        return 'Ограничена';
      case 'expired':
        return 'Истекла';
      case 'disabled':
        return 'Отключена';
      default:
        return 'Неизвестно';
    }
  }

  /**
   * Clear cache (useful for manual refresh)
   */
  clearCache(): void {
    this.cache.clear();
  }
}

// Singleton instance
export const marzbanApi = new MarzbanApiClient();